Never been bitten! My Goldfish though tried the othernight, he thought it was feeding time even though we had just finished dinner, but I I pushed him out of my way! lol.. Was trying to move a plant to get at a bottom feeder for pics.
I've got nibbled by small fish like barbs,Nothing really happens.
Worst thing that ever happened to me in that department is to get poked by my featherfin. It was like a needle and it drew blood.
My GBR's and Brevis Katabe are vicious lil fishies when they have eggs or fry in the tank. GBR's do more of a bump, but my Brevis male is hard core. He will nibble untill he get a bit of loose skin, then he bites down and trys to take a chunk away with him.
My mudskippers bite me every time I feed them. They are just trying to get the food first but it feels pretty strange. Kinda crunchy but they haven't broken my skin.